public final class Node {// 用于存储已落子坐标(x,y)
	int x;
	int y;

	Node() {
	}

	Node(int x, int y) {
		this.x = x;
		this.y = y;
	}

	@Override
	public String toString() {
		return "Node{" + "x=" + x + ", y=" + y + '}';
	}
}